It conventionally has been known that titanium oxide has a photo-catalytic action and thereby decomposes organic matters. The mechanism of decomposing organic matters by the photo-catalytic action can be explained as follows. More specifically, when titanium oxide is irradiated with light beam such as visible radiation, ultraviolet rays, and the like, charge separation occurs so as to generate electrons and highly oxidizable electron holes. The electron holes react with water vapor or oxygen in the air to generate reaction active species such as OH radicals, O.sub.2.sup.-, etc. Such reaction active species instantaneously decompose organic matters existing around them. At present, titanium oxide is used for the purpose of environmental clean-up, for example, a deodorizing purpose, stain resisting purpose, an antibacterial purpose, etc. by using the photo-catalytic action.
However, when titanium oxide is used in a field of fibers, there are the following problems. First, since titanium oxide is provided in a form of powder, it can be mixed and added to the interior of synthetic fibers. However, since there is no effective method for attaching titanium oxide to natural fibers such as wool, cotton, etc., it has been difficult to attach titanium oxide to natural fibers. Furthermore, even if titanium oxide is attached to natural fibers by some means, the portion of the natural fiber to which titanium oxide is attached is deteriorated by the strong photo-catalytic action of titanium oxide and titanium oxide is easily peeled off. Moreover, as mentioned above, titanium oxide is activated only when ultraviolet rays are present in light to some extent, therefore titanium oxide does not exhibit a sufficient effect inside the house. Furthermore, when titanium oxide is allowed to attach to an animal fiber including protein as a main component, the fibers turn yellow due to the influence of titanium ion.
It is therefore an object of the present invention to provide a natural fiber containing titanium oxide that sufficiently exhibits various functions such as a deodorizing function, a stain resisting function, an antibacterial function, and the like, and to provide a process for producing the same by developing an effective method of attaching titanium oxide to natural fibers in which titanium oxide is not peeled off and no yellowing occurs.